feat(component context): export key

fix #85

Author: Larry Botha

lib/index.js

@@ -1,5 +1,9 @@
+import {key} from './components/key';
+
 export {createForm} from './create-form';
+
 export {default as Form} from './components/Form.svelte';
 export {default as Field} from './components/Field.svelte';
 export {default as Select} from './components/Select.svelte';
 export {default as ErrorMessage} from './components/ErrorMessage.svelte';
+export {key};